Heat transfer systems are known, such as mixing circuits (mixing loops) in heating installations, with which a part of the return flow from a load circuit is admixed again to the feed of the load circuit, in order to reduce the temperature in the feed. As a rule, a valve and a pump are provided for this, wherein the valve, via which the admixing is regulated (closed-loop controlled), is regulated in dependence on the temperature in the feed to the load circuit. Independently of this, as a rule the pump in the load circuit is regulated with regard to its speed in a pressure-dependent manner. Moreover, it is also known to apply heat transfer systems with heat exchangers in heating installations, wherein one side of the heat exchanger is connected to a supply conduit for heating medium and the other side of the heat exchanger is connected to a load circuit. As a rule, a delivery pump is provided in the load circuit, and a valve in the supply conduit, via which valve the quantity of the fed heating medium is regulated depending on the temperature in the load circuit. Here too, the temperature regulation takes place independently of the pressure regulation, via the speed of the pump. The disadvantage of these systems is the fact that this can lead to sluggishness at high loads as well as to an oscillation of the regulation at part loads.